The present invention relates to a push button device for electric contacts or the like, particularly suitable for instrumentation panels.
More particularly, the present invention relates to a device of the kind mentioned above, which device controls a system of springs and small cylinders through the axial movement of a push button, said springs and cylinders, by moving in turn axially, realizing the contact with an electric or a printed circuit.
A number of solutions have been proposed and realized in the technical field in which the devices of the type the present invention deals with are employed, but said solutions, though sufficiently reliable for the desired uses, give rise to a series of drawbacks that make it difficult to employ the same.
More particularly, the push button device MARK 21 of JAY-EL PRODUCTS, INC. is characterized by the lack of tactile sensation on the user's part.
Such a drawback has been overcome by the device of SYMBOLIC DISPAYS, INC., which are realized employing a synthetic material bulb. Such type of solution shows a tendency to frequent breakage so that it cannot be considered reliable.
Another kind of solution adopted makes use of a contact bearing a printed circuit realized direct on said contact, on a very small area of the same, so that a very large deterioration of the contact points occurs. Moreover, in the case of such solution the tactile sensation is completely lacking.
One of the most advanced systems known (U.S. Pat. No. 4,088,855 for Korry Manufacturing Company) in the technical field makes use of an an annular spring which, by moving axially and laterally under the pressure of a button, realizes the contact. In that way, though the user has the tactile sensation of pushing the button, the danger of device failure if the spring breaks is not completely eliminated, and, in addition, as said spring is in direct contact with the printed circuit, even though on a larger area, it tends to wear said circuit, so that the risk of device failure increases.